1. Field of the Invention
The invention relates generally to the fields of autoimmunity and inflammatory bowel disease and more specifically to genetic methods for diagnosing Crohn's disease and other autoimmune diseases.
2. Background Information
Inflammatory bowel disease (IBD) is the collective term used to describe two gastrointestinal disorders of unknown etiology: Crohn's disease (CD) and ulcerative colitis (UC). The course and prognosis of IBD, which occurs world-wide and is reported to afflict as many as two million people, varies widely. Onset of IBD is predominantly in young adulthood with diarrhea, abdominal pain, and fever the three most common presenting symptoms. The diarrhea may range from mild to severe, and anemia and weight loss are additional common signs of IBD. Ten percent to fifteen percent of all patients with IBD will require surgery over a ten year period. In addition, patients with IBD are at increased risk for the development of intestinal cancer. Reports of an increasing occurrence of psychological problems, including anxiety and depression, are perhaps not surprising symptoms of what is often a debilitating disease that strikes people in the prime of life.
A battery of laboratory, radiological, and endoscopic evaluations are typically combined to derive a diagnosis of IBD and to assess the extent and severity of the disease. Nevertheless, differentiating Crohn's disease from ulcerative colitis, as well as other types of inflammatory conditions of the bowel, such as irritable bowel syndrome, infectious diarrhea, rectal bleeding, radiation colitis and the like, is difficult because the mucosa of the small and large intestines reacts in a similar way to a large number of different insults. Furthermore, the extensive and often protracted clinical testing required to diagnose CD delays accurate diagnosis and treatment and involves invasive procedures such as endoscopy.
To date, a reliable genetic test for Crohn's disease, which would be highly prized as a non-invasive method for the early diagnosis of Crohn's disease, is not available. Such a test, based on identifying genetic markers that are associated with a predisposing mutation to an autoimmune disease such as Crohn's disease, would obviate invasive clinical procedures. Such a genetic assay also would be useful in methods of predicting susceptibility to Crohn's disease in asymptomatic individuals, making prophylactic therapy possible. Unfortunately, genetic markers closely associated with Crohn's disease have yet to be identified. The present invention satisfies this need and provides related advantages as well.